Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Boeing Model 737-100 and -200 series airplanes. This proposal would require repetitive inspections to find fatigue cracking in the main deck floor beams located at certain body stations, and repair, if necessary. This proposal also provides for optional terminating action for the repetitive inspections. This action is necessary to prevent failure of the main deck floor beams at certain body stations due to fatigue cracking, which could result in rapid decompression and consequent reduced controllability of the airplane. This action is intended to address the identified unsafe condition.